Modulation of Galactic Cosmic Rays in the Inner Heliosphere over Solar Cycles

Abstract

The 11-year and 22-year modulation of galactic cosmic rays (GCRs) in the inner heliosphere are studied using a numerical model developed by Qin and Shen in 2017. Based on the numerical solutions of Parker's transport equations, the model incorporates a modified Parker heliospheric magnetic field, a locally static time delayed heliosphere, and a time-dependent diffusion coefficients model in which an analytical expression of the variation of magnetic turbulence magnitude throughout the inner heliosphere is applied. Furthermore, during solar maximum, the solar magnetic polarity is determined randomly with the possibility of $A>0$ decided by the percentage of the north solar polar magnetic field being outward and the south solar polar magnetic field being inward. The computed results are compared with several GCR observations, e.g., IMP 8, SOHO/EPHIN, Ulysses, Voyager 1 \& 2, at various energies and show good agreement. It is shown that our model has successfully reproduced the 11-year and 22-year modulation cycles.

arXiv commentAccepted for publication in The Astrophysical Journal

References in corpus (26)

• Solar Modulation of Cosmic Rays
• Time dependence of the proton flux measured by PAMELA during the July 2006 - December 2009 solar minimum
• Measurements of 0.2 to 20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer
• Modulation of galactic protons in the heliosphere during the unusual solar minimum of 2006 to 2009
• Solution of heliospheric propagation: unveiling the local interstellar spectra of cosmic ray species
• Systematic Investigation of Solar Modulation of Galactic Protons for Solar Cycle 23 using a Monte Carlo Approach with Particle Drift Effects and Latitudinal Dependence
• Diffusion and drift of cosmic rays in highly turbulent magnetic fields
• Propagation of Cosmic Rays in Heliosphere: the HelMod Model
• Perpendicular Diffusion of Solar Energetic Particles: Model Results and Implications for Electrons
• Modulation of galactic cosmic rays during the unusual solar minimum between cycles 23 and 24
• A generalized two-component model of solar wind turbulence and ab initio diffusion mean free paths and drift lengthscales of cosmic rays
• Cosmic Ray Diffusion Coefficients Throughout The Inner Heliosphere From Global Solar Wind Simulation
• New local interstellar spectra for protons, Helium and Carbon derived from PAMELA and Voyager 1 observations
• Time-Dependent Modulation of Cosmic Rays in the Heliosphere
• The effect of magnetic field modifications on the modulation of cosmic rays in the heliosphere
• Global gradients for cosmic-ray protons in the heliosphere during the solar minimum of cycle 23/24
• Modulation of Galactic Cosmic Rays in the Inner Heliosphere, Comparing with PAMELA Measurements
• The Modification of the Nonlinear Guiding Center Theory
• Annual Cosmic Ray Spectra from 250 MeV up to 1.6 GeV from 1995 - 2014 Measured With the Electron Proton Helium Instrument onboard SOHO
• Implementing turbulence transport in the CRONOS framework and application to the propagation of CMEs
• A Generalized Diffusion Tensor for Fully Anisotropic Diffusion of Energetic Particles in the Heliospheric Magnetic Field
• On the relationship of the 27-day variations of the solar wind velocity and galactic cosmic ray intensity in minimum epoch of solar activity
• Quasilinear Drift Of Cosmic Rays In Weak Turbulent Electromagnetic Fields
• Latitudinal Dependence of Cosmic Rays Modulation at 1 AU and Interplanetary-Magnetic-Field Polar Correction
• Voyagers 1 and 2 in a Shrunken and Squashed Heliosphere
• Cosmic-ray diffusion in a sectored magnetic field in the distant heliosheath

Cited by in corpus (6)

• Variations of the Galactic Cosmic Rays in the Recent Solar Cycles
• Effects of shock and turbulence properties on electron acceleration
• Unfolding Drift Effects for Cosmic Rays over the Period of the Sun's Magnetic Field Reversal
• A Model of Sunspot Number with Modified Logistic Function
• Magnetic Cloud and Sheath in the Ground-Level Enhancement Event of 2000 July 14. II. Effects on the Forbush Decrease
• Solar modulation of cosmic proton and helium with AMS-02